From: Hans Hagen <j.hagen@xs4all.nl>
To: mailing list for ConTeXt users <ntg-context@ntg.nl>,
Rudolf Bahr <quasi@quasi.de>
Subject: Re: When newsizing an external figure bei [width=<some pt>], what will be its height in pt and viceversa?
Date: Sat, 23 Feb 2019 11:56:32 +0100 [thread overview]
Message-ID: <e6b297a6-9870-2467-610d-436f18f1fd53@xs4all.nl> (raw)
In-Reply-To: <20190223100818.t5azu6c2hgaps6pe@nan>
On 2/23/2019 11:08 AM, Rudolf Bahr wrote:
> On Fri, Feb 22, 2019 at 12:59:55PM +0100, Peter Münster wrote:
>> On Fri, Feb 22 2019, Rudolf Bahr wrote:
>>
>>> The picture sizes in px One gets by invoking for instance graphics Magick's identify
>>> in a lua program:
>>
>> Or just img.scan():
>>
>> \startluacode
>> local image = img.scan{filename = "my-image.jpg"}
>> logs.report("xsize", image.xsize)
>> logs.report("ysize", image.ysize)
>> \stopluacode
>>
>> --
>> Peter
>
> Hi Peter,
>
> thank you for pointing to img.scan{}! It's indeed shorter than to invoke Graphics Magick
> in Lua. Remains the conversion of image sizes into pt. There is an example in the chapter
> "Calculations in Lua" in "https://wiki.contextgarden.net/Image_Placement" (a work in
> progress). According to there it's necessary to know the resolution in order to convert
> image sizes from px to pt which at least I don't know. Mostly I can preset one size of
> a picture (say the width in pt) to be able to place it on a page and assuming
> x-resolution = y-resolution and keeping width-to-height ratio I calculate the missing
> size (here the height in pt) in Lua by
>
> picture-height-in-px
> asked-picture-height-in-pt = preset-picture-width-in-pt * --------------------
> picture-width-in-px
>
> This is simple and normally it suffices for me.
Better use the built-in methods:
\starttext
\getfiguredimensions[t:/sources/mill.png]
(\figurewidth,\figureheight)
(\figurexsize,\figureysize)
\stoptext
as it prevents opening the files multiple times. It's also more futureproof.
Hans
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next prev parent reply other threads:[~2019-02-23 10:56 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-19 9:48 Rudolf Bahr
2019-02-22 9:14 ` Rudolf Bahr
2019-02-22 11:59 ` Peter Münster
2019-02-23 10:08 ` Rudolf Bahr
2019-02-23 10:56 ` Hans Hagen [this message]
2019-02-23 11:37 ` Rudolf Bahr
2019-02-23 11:48 ` Hans Hagen
[not found] <mailman.727.1550955497.1205.ntg-context@ntg.nl>
2019-02-23 22:38 ` Jeong Dal
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